Hi,
I think I have it all in this answer. If you find I didn't cover
something as much as you would have liked, just let me know through
the clarification option and I'll look further into that area.
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1) WEAR DEBRIS ANALYSIS:
any TWO techniques of the following would suffice:
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Inductive sensors
Reference Links,
Steel Wire Rop Contition Monitoring by Non-Destructive Investigation
http://www.ndt.net/article/wcndt00/papers/idn072/idn072.htm
Mathematical model for the determination of the vertical displacement
from internal horizontal measurements of a bridge
http://www.lucidmatrix.com/uploads/Mathematicalmodeldeterminationverticaldisplacement.pdf
Allegro Hall Effect Sensors
http://www.allegromicro.com/hall/
mode of application
The other tests described in here use the hall effect sensors, which
flood the negative magnitic charge into a cable. Reading the referance
pages at the top will clear this up for you. There appears to be
several types of Inductive sensors used for non-destructive testing,
so I've picked the main two that I found and focused there.
(see reference page for sketches and reading examples as well as other
information.)
principle of operation with aid of sketches
PRINCIPLE OF OPERATION:
Localized faults in a rope are detected using inductive sensors and
distributed flaws in a rope is determined by using Hall Effect
sensors. The sensing head bring the running sector of wire rope to a
condition close to magnetic saturation and provides signal from its
sensors. The inductive sensors detect signals due to localized loss
viz. broken wires, pitting localized corrosion and the distributed
loss of metallic cross sectional area are sensed by Hall Effect
sensors for evaluation of defects caused due to corrosion wear and
abrasion.
The developed eddy current sensors can be applied to the force and
stress measurement of tensioned steel elements, the monitoring of
pre-stressed bridge cables and concrete structures etc.
(see reference page for sketches and reading examples as well as other
information.)
advantages
Visual inspection of wire rope for the in service inspection of wire
ropes had deficiencies. It has been concluded that non destructive
examination of wire ropes in mining and aerial ropeway industries
where ropes play a vital role and the data obtained from
non-destructive investigations at periodic interval will assist in
developing future ropes safety standards and in determining wire rope
extension/premature retirement criteria.
Non contact
Ignores non metallic objects e.g: dirt, water lubricating oil
limitations
Unless shielded, individual sensors must be spaced to avoid cross
talk.
No zero speed measurement of moving objects.
practically
Very practical. The equipment is portable and doens't require the use
of a lab to get results.
plus examples of where it could be used in machinery on board ships
Any area where steel cable or steel is under a constant strain. Tow
cables, crane cables, holds, and pressure canisters.
ABSTRACT
Steel wire ropes are extensively used in mining/ Aerial ropeway
industries for haulage, track and hoisting purposes for transportation
of men & materials. The importance of periodic rope condition
monitoring plays a vital role to achieve maximum mineral exploitation
in the hazardous atmosphere as well as passenger cable car ropeway
installations. With fast approach in mechanization in mining
industries/ passenger cable car ropeway installation, adoption of
latest technology in non-destructive investigation and evaluation to
enhance safety and optimum safe rope life is essential and Central
Mining Research Institute is engaged in this endeavour since last more
than three decades.
http://www.ndt.net/article/wcndt00/papers/idn072/idn072.htm
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Capacitive sensors
mode of application
Active: electrodes generate and shape an electric field. Objects with
a dielectric value affect the capacitance between the electrodes which
is detected via the sense electrode. Often only one electrode, the
sense electrode, is required.
Range: low.
Output: analogue or digital (set-point).
Sensing elements: charged and sense electrodes, (any material capable
of being electrically charged).
Property in target essential to operation: permitivity variation to
background.
principle of operation with aid of sketches
Capacitance is a measure of the ability of an object to store
electrical charge. In its simplest form, this "object" is two
electrodes separated by an air gap of some distance d. As the
electrodes are moved closer to or farther from one another, the air
gap, d, changes, and therefore so does the capacitance. Pressure
Profile Systems uses this principle to determine the pressure applied
to a sensor, an approach that has several advantages. First, the
simplicity of a capacitor allows for a great deal of flexibility in
design and construction, allowing us to build sensors as conformable,
multi-element arrays (See below). Second, the two electrodes are
non-contacting since they are always separated by an air gap, which
means results are more repeatable and sensor performance is less
likely to degrade over time. Finally, capacitive sensors are more
sensitive and more resistant to changes in operating temperature. The
following table shows a comparison of capacitive sensors versus the
two other most common approaches, Resistive-based and Piezoelectric
pressure sensors.
advantages
Non-contact.
Detection of metallic or non-metallic objects.
Light and sound immune.
Ability to detect targets non invasively (through other materials).
Can distinguish mass, e,g between un compressed dust powder and
greater mass of material.
Can compensate for: dirt build-up, change in temperature or humidity
in sensing field region.
Can shape or direct sensing field and focus detection into defined
areas.
Multiple receiving electrode arrays can be used without cross talk.
limitations
In their simplest form capacitive sensors cannot distinguish between
different objects which present the same relative permitivity.
Again in simplest form can be sensitive to temperature and humidity
swings.
Capacitive sensors need an electrical contact with the 'other'
surface. These restrictions make their use difficult in many
applications.
practically
Experimental smart coatings that have been developed thus far
include crackwires (for detecting cracks and plastic deformation at
instrumented surfaces); eddy-current sensors for detecting plastic
deformations below the instrumented surfaces; and capacitive
sensors for detecting surface contamination (e.g., fuel, ice, or
water).
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2) VISUAL INSPECTION (Crack detection):
SIX techniques are required:
Dye penetrants,
mode of application
Penetrant fluid is applied to the surface of the test object and
penetrates into any cracks.
Penetrant fluid is removed from the surface but not from the cracks.
The developer acts as a blotting paper and sucks up penetrant fluid
from the crack.
principle of operation with aid of sketches
advantages
highly effective for surface defects
used mostly to detect tiny cracks in the surface
limitations
manual and slow
only used to detect defects appearing on the surface of the material
practically
used in combination with other non-destructive testing such as
radiographic or Eddy Current testing.
Liquid penetrant inspection is a method that is used to reveal surface
breaking flaws by bleedout of a coloured or fluorescent dye from the
flaw.
The technique is based on the ability of a liquid to be drawn into a
"clean" surface-breaking flaw by capillary action. After a period of
time called the "dwell", excess surface penetrant is removed and a
developer applied. The developer acts as a "blotter". It draws out the
penetrant from the flaw to reveal its presence on the surface. Colour
contrast penetrants require good white light while fluorescent
penetrants need to be used in controlled darkened conditions with an
ultraviolet "black light".
Penetrant inspection can be used on any solid material. It is
essential that the material is carefully cleaned first, otherwise the
penetrant will not be able to get into the flaw. If surface penetrant
is not fully removed, misleading indications will result.
plus examples of where it could be used in machinery on board ships
This type of testing is possible everywhere on a ship. Visual and dye
type discoveries are part of the daily tasks. Even if this is not the
most defined method of discovery, it is the most obvious.
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Ultrasonic,
mode of application
a frequently prescribed testing method for seamless tubes.
Active: A piezo transducer generates ultrasonic waves (short
wavelength, high frequency normally outside the audible frequency)
which are reflected by suitable target objects (echo). The reflection
is received by a piezo transducer and time of flight is calculated to
determine range to object.
Can be used internally if coupled to a surface where internal
reflection will occur at changes in material consistency. (medical
ultrasound)
Passive? See acoustic emission.
Range: to 20m
Sensing elements: transmitting piezo transducer, receiving transducer
(often same transducer when not transmitting).
Property in target essential to operation: ability to reflect
ultrasound waves, or if used as through beam, to absorb or break
waves.
performed on sheet-welded tubes as a method of inspecting the sheet
edges
normally limited to plate with a thickness > 5 mm.
principle of operation with aid of sketches
advantages
Vibration of piezo transducer has self cleaning effect.
Longer range capability normally than capacitive or inductive
techniques.
Can do background suppression. (able to tune out range >X).
limitations
Single transducer types feature a dead band over the time period to
dampen transmission oscillations.
The speed of sound varies according to temperature and pressure of the
medium, changes or gradients affect accuracy and may require
compensation.
Freezing can affect transducers esp. if ice forms
not suitable for inspection of austenitic welds because the residual
solidification structure is relatively coarse and giving echoes that
interfere with the evaluation
occasionally required on welded heat exchanger tubes, in spite of its
unsuitability
practically
usually carried out manually and therefore expensive
Ultrasonic inspection uses sound waves of short wavelength and high
frequency to detect flaws or measure material thickness. It is used as
an alternative inspection method to radiography to locate sub-surface
flaws in all industry sectors.
Usually, pulsed beams of high frequency ultrasound are used via a hand
held transducer (probe) which is placed on the specimen. Any sound
from the pulse that is reflected and returns to the transducer (like
an echo) is shown on a screen, which gives the amplitude of the pulse
and the time taken to return to the transducer. Flaws anywhere through
the specimen thickness reflect the sound back to the transducer. Flaw
size, distance and refectivity can be interpreted.
Automated systems are used for testing in a production environment and
for some special applications.
plus examples of where it could be used in machinery on board ships
Ultrasonic Hull Thickness Measurements
Ultrasonic Thickness Measurement Surveys (U.T.M.) on Ship’s Hull
Structures during
1. Ballast Voyage using Riding Crews
2. Discharge Turnarounds
3. Alongside Repair Quays in Ports
4. Drydocks
Steel Condition Assessment
Renewal planning by indicating condition of steel, highlighting areas
of serious wastage, fracturing or buckling based on gauging results,
visual inspection & photography.
Indicating cropping lines for renewal or re-coating and if necessary,
calculation of steel weights
Providing draft reports at sea during ballast voyage, thus informing
Ship Owner in advance, prior to drydocking or lay-up
On-board desktop CAD Operators to simultaneously process incoming
inspection data results on a daily basis ensuring the immediate
production & delivery of your inspection report prior to the vessel's
arrival at the destination port.
Riding Crew Welders for Minor Steel Repairs
We provide qualified "Class-Approved" Welders to carry out weld
repairs during ballast voyages in order to rectify any outstanding
"Condition of Class" items or any structures found defective during
Close-Up Survey.
4. Bottom Shell Pitting (Tankers)
Mapping the extent and severity of individual pits by way of
systematically checking pitting corrosion in each bay
5. Close-Up Survey (Tankers)
Visual examination and U.T.M. gauging of ballast tanks carried out
during ballast voyage using either flotation rafts or Rope Access
techniques
(See "Ultra-Access")
These methods enable safe access to high-level areas of structure
6. CAD Operators
Upon request, we can provide an "on-board" desktop CAD operator as
part of our Riding Crew to ensure the immediate production & delivery
of your inspection report prior to the vessel's arrival at the
destination port
The CAD operator simultaneously processes incoming inspection data
results on a daily basis (ie. Gauging spreadsheets, Steel Renewal
calculation spreadsheets, incorporating digital photographs as part of
your final report)
7. Testing Equipment Used
Latest state of the art ultrasonic portable digital gauges with data
logging capabilities
Portable digital LCD A-Scan ultrasonic flaw detectors are used for
verification if required
Multiple echo digital gauges provide accurate thickness measurement
through paint coatings without chipping or damaging the coating
Ultrasonic Hatch Cover Tightness Testing
Efficient alternative to conventional water hose testing
Time saving method using panoramic ultrasonic generator (transmitter)
and receiver detector
Tightness test can be carried out with or without cargo in holds and
even at sub-zero temperatures
Avoid possible unexpected hatch cover repair costs
Equipment accepted by all major Classification Societies
Useful for steel cargo charterers and various P & I Clubs
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Radiography
complete answer for this area is described on this web page :
Non-Destructive Testing Micro-Focus X-Radiography
http://www.azom.com/details.asp?ArticleID=1437
Radiographic inspection is primarily used to find sub-surface flaws in
materials.
High voltage x-ray machines produce X-rays whereas gamma rays are
produced from radioactive isotopes such as iridium 192. The chosen
radiation source is placed close to the material to be inspected and
the radiation passes through the material and is then captured either
on film or digitally.
The choice of which type of radiation is used (x-ray or gamma) largely
depends on the thickness of the material to be tested and the ease of
access to area of inspection. Gamma sources have the advantage of
portability, which makes them ideal for use in construction site
working. High energy portable x-ray machines are available for special
applications such as concrete structures.
X-rays and gamma rays are very hazardous. Special precautions must be
taken when performing radiography. Therefore the method is undertaken
under controlled conditions, inside a protective enclosure or after
assessment with appropriate barriers and warning systems to ensure
that there are no hazards to personnel.
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Eddy current,
References
Inductive Eddy Current Sensors
http://www.chenyang-ism.com/EddyCurrent.htm
mode of application
An eddy current sensor consists of a ferrite U-core and a coil. The
force and stress measurement is based on the permeability change of
the device under test (DUT) caused by an applying force on it. As
result the impedance of the sensor coil changes with the applying
force. The impedance change can be converted into a voltage change by
using a measuring bridge. The force and stress applied on the DUT can
be derived by the voltage measurement.
A coil applies alternating magnetic fields to a target object, this
generates electrical currents (eddy currents: because they flow in
circles) below the surface of the target object. These eddy currents
are disturbed by geometry changes including those caused by corrosion
or hairline cracks. Coil impedance responds to changes in the eddy
current flowing in the target object. The change in impedance is
measured.
The Eddy current technique only applies to conductive materials and is
used extensively in non destructive testing.
principle of operation with aid of sketches
The method consists of primary coils in a system of coils that are
energized with alternating current which creates a magnetic field in
the tube. This magnetic field, in turn, gives rise to a voltage across
two similar but oppositely wound secondary coils. When, for instance,
a weld defect passes the system of coils, the voltage across the
secondary coils will be different and consequently a defect signal is
obtained. A defect signal of this nature from a natural defect can
then be automatically compared with the defect signal from an
artificial defect prescribed in the testing standards, i.e. a test
defect. These test defects may be drilled holes of a certain diameter,
or grooves of a certain length and width and with a depth which is
usually expressed as a percentage of the wall thickness.
As a rule, Eddy Current testing takes place as final testing in a
separate testing line. Here, testing of the entire tube cross-section
takes place with surrounding coils, which may be either single or
segment coils.
Testing can also take place directly in the welding line. This testing
can also be carried out with different types of surrounding coil
systems, but testing with surface probes (which only cover the actual
weld zone) is also employed.
Eddy Current testing is prescribed at two different levels with two
different objectives:
testing as an alternative to hydrostatic testing (e.g.
SS 114305-E1, SEP 1925)
testing of the weld in order to utilize the weld factor 1.0 (e.g. SS
114304-E2, SEP 1914).
As a substitute for hydrostatic testing, this method is approved by
several authorities who insist only upon testing with surrounding
coils. A surrounding coil test of the weld according to level 2, (as a
basis for weld factor 1.0) is obviously also acceptable as a
substitute for hydrostatic testing.
Certain authorities also accept testing in the welding line as a final
test. This also applies to testing of the weld only, with surface
probes. Testing in the welding line is also used as a purely internal
manufacturing inspection method, enabling any welding defects to be
not only detected but also eliminated as early as possible.
advantages
Ideal and well developed solution for non-invasive non destructive
testing within metal parts.
the most common non-destructive method of testing thin-walled welded
tubes
a fast, efficient and accepted method of testing
the base for welding factor 1.0 in Europe
a substitute for hydrostatic testing
is normally not used on tubes with wall thickness above 5 mm.
limitations
Limited developments for other applications.
practically
the most common non-destructive method of testing thin-walled welded
tubes
a fast, efficient and accepted method of testing
plus examples of where it could be used in machinery on board ships
Any surface that is welded can benifit from this test.
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Stroboscopes
mode of application
stroboscopes are designed for quality control, motion analysis,
vibration problems, maintenance work, experiments in engineering
school projects, production line checks, examination and speed
measurement of motors under various loads, gear movement and
engagement, alignment of parts, cams, propellers, fan blades,
centrifuges, spindles, turbines and other machinery exhibiting
repetitive motion. They also can provide pertinent information on the
motion of vibrating parts, oil leaks, liquid spray patterns and a host
of other industrial and scientific applications. Unique instruments
for the printing industry to check color registration, ink integrity,
clarity, etc.
principle of operation with aid of sketches
Stroboscopes allow maintenance personnel to visually ‘freeze’ rotating
equipment during normal operation. This stop-action technique is
ideally suited for isolating such faults as mis-aligned belts, shaft
alignment, rotor imbalance as well as damage to fan blades and other
similar rotating equipment. A stroboscope can also be used to
determine turning gear rpm as a secondary function.
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and Magnetic flux.
Reference.. and complete answer for this testing can be found in this
PDF file
http://www.lucidmatrix.com/uploads/mag_flux_dye.pdf
Magnetic particle inspection is a method that can be used to find
surface flaws in ferromagnetic materials such as steel and iron.
The technique uses the principle that magnetic lines of force (flux)
will be distorted by the presence of a flaw in a manner that will
reveal its presence. The flaw (for example, a crack) is located from
the "flux leakage" following the application of fine iron particles to
the area under examination. There are variations in the way the
magnetic field is applied, but they are all dependent on the above
principle.
The iron particles can be applied dry or wet, suspended in a liquid,
coloured or fluorescent. While magnetic particle inspection is
primarily used to find surface breaking flaws, it can also be used to
locate sub-surface flaws. The method's effectiveness quickly
diminishes depending on the flaw depth and type.
Surface irregularities and scratches can give misleading indications.
Therefore it is necessary to ensure careful preparation of the surface
before magnetic particle testing is undertaken.
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3) NOISE MONITORING:
any TWO of the following:
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Impulsive noise monitoring,
mode of application
Use an impact-noise meter with peak hold capability to measure impact
noise. The inertia of the indicating meters of general-purpose sound
level meters prevents accurate, direct measurements of single-impulse
noises that change level significantly in less than 0.2 second. A low
inertia device such as an oscilloscope must be used to measure these
impulse-type noises if detailed information is required.
principle of operation
Sound is produced by a sudden local compression of a gas, liquid or
solid. The compression may be a single pulse (bang!), a group of
pulses (speech), or a periodic pulse (musical tone). It is then
transmitted through the neighbouring media by pressure waves
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infrasonic
mode of application
The pulse-echo technique is used for non-destructive testing of
materials.
For example, cracks inside pillars will reflect waves back, so by
sweeping a narrow beam of sound backwards and forwards, this will give
the size and depth of any internal cracks as well as the wall
thickness.
Infrared thermography is a form of non-contact, non-destructive
testing used to detect and document thermal patterns and associated
temperatures across a given surface. Performed regularly, infrared
inspections can help to identify latent equipment failures.
principle of operation with aid of sketches
Sound is only audible to the average human ear if the frequencies lie
between 20Hz and 20kHz. The actual range varies from person to person.
Sound waves with frequencies less than 20Hz are called infrasonic and
those with frequencies above 20kHz are called ultrasonic.
Infrasonic (or "subsonic") wave pulses (< 20Hz ) are produced by a
number of geophysical processes such as avalanches, earthquakes and
various explosions, geomagnetic variations, meteors, ocean waves,
severe weather and volcanos.
Early detection of infrasonic waves that signify dangerous situations
can provide warnings to nearby populations.
Aircraft and other industrial machinery (e.g. jack hammers) also cause
infrasonic waves that can be harmful to some human internal organs.
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A-weighting,
Answer for this section is supplied by the following link
A Weighting filter
http://sound.westhost.com/project17.htm
A-weighted. Weighting is an equalization (EQ) process used to
apportion the influence of different frequency regions on an audio
measurement, usually one of noise level. "A" weighting was developed
to imitate the ears' sensitivity to low-level sounds (below 70 dB SPL)
and is used in Sound & Vision's measurements of noise (see S/N). The
A-weighting curve rolls off below 1 kHz and above 6 kHz and slightly
boosts the upper-midrange frequencies in between.
Early attempts to improve on basic noise measurement used what came to
be referred to as the 'A' Weighting curve, which had been derived from
the work of Fletcher and Munsen (1933) who investigated hearing
variation with frequency and found that they needed to plot a set of
'equal loudness' contours because the ears frequency response was
different at different loudness levels. The curve representing
loudness equal to that at 1kHz and 40dB SPL (sound pressure level) was
known as the 40-phon curve, and was (supposedly) adopted for weighting
purposes. Later work by Robinson and Dadson (1956), refined the method
producing significantly different, and more accurate curves however.
In 1968, two inventions began to make clear the inadequacy of
A-weighting; the introduction of FM Radio and the Compact Cassette.
The latter in particular, was found to sound a lot less noisy (10dB)
with Dolby noise reduction switched on, without measuring
significantly better, and this led to work on better ways of measuring
noise. The BBC (British Broadcasting Corporation) undertook a research
project, culminating in BBC Research Dept Report EL-17 entitled "The
Assessment of Noise in Audio Frequency Circuits", in which they
studied the effectiveness of various wieghting curves and rectifiers
that had been devised by the world's broadcasters, on all sorts of
extreme noise sources, and they chose one combination as being very
effective. Later work refined this into what became a world standard
known as CCIR468, which, though it has gone through versions 1 to 4 is
still essentially unchanged, only the permitted tolerances being
altered. Unfortunately, though CCIR468 was adopted by many major
broadcasting organisations, and also incorporated into standards from
BS (British Standards) and IEC (International Electrotechnical
Commission) to EBU (European Broadcasting Union), and for a while even
became championed in consumer reviews of Cassette Decks (notably by
Angus McKenzie in the 1970's) it is now falling into disuse for one
simple reason: in an age when advertising rules, big figures are
reckoned to sell products, even if they are meaningless, and
A-weighting gives bigger numbers.
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Spectral analysis or
References
Evaluation/Characterization of Airport Pavements Using Impact-Echo and
Spectral Anaylsis of Surface Waves
http://uiairpave.ce.uiuc.edu/enhanced/research/projects/impact.html
mode of application
Ultrasonic spectroscopy denotes the methods used to analyze the
frequency components of ultrasonic signals that are wideband pulses.
When an ultrasonic signal traverses a medium, the frequency components
associated with the input signal are altered. To produce the frequency
domain information a discrete Fourier transform can be used. It is
possible to study the effect of material properties on the alteration
of the input signal subjecting to frequency-spectrum analysis the echo
or transmitted pulse for different materials. A given input impulse
will emerge having different frequency spectra after traversing
dissimilar materials. Spectrum analysis essentially gives an
ultrasonic"signature" that is generic to the particular microstructure
type concerned.
An important application of the frequency-spectrum analysis involves
the differential analysis of successive echoes. Each successive time
domain echo will be more attenuated than its predecessor. In the
frequency domain the ratio of the amplitudes for a series of frequency
components represents the basis for determining a functional relation
between the attenuation coefficient and frequency, (f).
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FFT/ZoomFFT.
(full answer to this section at these links)
An Introduction to Fourier Theory
http://aurora.phys.utk.edu/~forrest/papers/fourier/
The FFT Demystified
http://www.eptools.com/tn/T0001/INDEX.HTM
1. Short history
We owe our knowledge of the treatment of the signal in major part to
the Baron Joseph FOURIER (Auxerre 1768 - Paris 1830) who, by studying
the propagation of heat, discovered the said trigonometrical series
Fourier series. He improved this powerful mathematical tool to apply
it to any type of signal. Since a score of year only, the electronic
tools made it possible to apply these mathematical formulas, thanks in
particular to American COOLEY and TUKEY. They gave rise to the
calculation algorithm FFT (Fast Fourier Transform) which one finds in
the majority of the analyzers of the market.
2. Theoretical operation of the FFT Theorem of Fourier: Any
continuous function is decomposable in Fourier series. If moreover
this function is periodic of period T, the number of terms of the
decomposition is finished. One can then write the function like a sum
of sine (or cosine) f(t) = A0 + A1 sin(2 P T/T) + A2 sin(2 P T/2T)
+... + An sin(2 P T/NT) where Have is the coefficient of the Fourier
series at the frequency fi = 1/iT. In practice that wants to say that
one can break up our function like a sum of sine (cosine) of multiple
periods of the basic period of our function. The coefficients then
represent (if one manages well in our calculation) energy level the
"of each elementary frequency". The principal application of analysis
FFT is thus the description of the periodicities of the signal and the
calculation of "the energy" contained in the signal for each
frequency. Also, analysis FFT is used to observe signals which are
not periodic (random for example). This extension of capacity of the
calculation FFT, which is not natural for this type of signal, calls
with the greatest prudence in the interpretation of the results. The
transform of Fourier is one of the methods (the most used today) to
represent a temporal phenomenon in the frequential field. This
frequential representation is an image among other possible studied
phenomenon. There are other more complex but more effective methods.
The comprehension of the FFT helps however with better
including/understanding them.
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Other Links of interest
The online Journal of Nondestructive Testing
http://www.ndt.net/
Sensing Solutions
http://www.sensatech.com/solutions/comparison_of_techniques.html
Human Reliability in Ultrasonic Inspection
http://www.ndt.net/article/wcndt00/papers/idn525/idn525.htm
Quality Assurance for Non-Destructive Testing
http://www.ndt.net/article/wcndt00/papers/idn599/idn599.htm
Sensors Magazin Article Index 1997
http://www.sensorsmag.com/articles/article_index/1997index.shtml
LiveAboard Magazine & Marine Chandlery
Engine Instruments
http://www.lmmc.com/articles/inst.htm
Querys Used for this answer
A-weighting Audio Measurements
"Inductive sensors" NON-DESTRUCTIVE TESTING
A-weighting "non destructive testing"
infrasonic "non destructive testing"
infrasonic non destructive testing
"Impulsive noise" monitoring non destructive testing
"Impulsive noise monitoring" non destructive testing
+"Capacitive sensors" non-destructive testing
+"Centrifuges" non-destructive testing
"Electric conducting filters" non-destructive testing
Spectrograph non-destructive testing
Spectography non-destructive testing
Stroboscopes
Magnetic flux Dye penetrants non-destructive testing
Hall Effect sensors
eddy-current testing by inductive sensors
Inductive sensors hull
"NON-DESTRUCTIVE TESTING
"Inductive sensors" NON-DESTRUCTIVE TESTING
Inductive sensors
Inverse transfer function method to estimate the combustion noise of
diesel engines
Mathematical model for the determination of the vertical displacement
from internal horizontal measurements of a bridge
...lots .. lots.. more..
Thanks,
webadept-ga |
